Chapter 12: Watershed management strategies

The tenets of watershed management – a focus on the land area linked to the water body, the incorporation of sound scientific information into the decision-making process and stakeholder involvement throughout the process – are well-suited for the management of cyanobacterial harmful algal blooms (C-HABs). The management of C-HABs can be viewed as having two main areas of focus. First, there is mitigation – control and/or removal of the bloom. This type of crisis response is an important component to managing active C-HABs and there are several techniques that have been successfully utilized, including the application of algicides, physical removal of surface scums and the mechanical mixing of the water column. While these methods are valuable because they address the immediate problem, they do not address the conditions that exist in the system that promote and maintain C-HABs. Thus, the second component of a successful C-HAB management strategy would include a focus on prevention. C-HABs require nutrients to fuel their growth and are often favored in longer-residence time systems with vertical stratification of the water column. Consequently, nutrients and hydrology are the two factors most commonly identified as the targets for prevention of C-HABs. Management strategies to control the sources, transformation and delivery of the primary growth-limiting nutrients have been applied with success in many areas. The most effective of these include controlling land use, maintaining the integrity of the landscape and applying best management practices. to prevent and control cyanobacterial harmful